Pen cap retainer



FIG. 1 is perspective view of the pen cap retainer showing my new design;

FIG. 2 is a left perspective view of the pen cap retainer thereof;

FIG. 3 is a front perspective view thereof;

FIG. 4 is a rear perspective view thereof;

FIG. 5 is a left side view thereof; and,

FIG. 6 is a right side view thereof.

The broken lines are included for the purpose of illustrating portions of the pen cap retainer and environmental features that form no part of the claimed design. 

CLAIM The ornamental design for a pen cap retainer, as shown and described. 